Hermetically enclosed small refrigerating machine

ABSTRACT

THE INVENTION RELATES TO A NOISE REDUCING ASSEMBLY FOR A REFRIGERATION UNIT OF THE HERMETICALLY SEALED TYPE. THE ASSEMBLY INCLUDES WALLS FORMING A HEAT INSULATING CHAMBER SURROUNDING THE NOISE REDUCING CHAMBER WITH A SUBSTANTIALLY STATICALLY CONTAINED GAS IN SAID HEAT INSULATION CHAMBER.

y 23, 1972 J. 0. KNUDSEN ETAL 3,664,769

HERME'IICALLY ENCLOSED SMALL REFRIGERATING MACHINE Filed Aug. 4, 1969FIGZ FIG]

KNUD VAGN VALBJORN United States Patent U.S. Cl. 417-312 2 ClaimsABSTRACT OF THE DISCLOSURE The invention relates to a noise reducingassembly for a refrigeration unit of the hermetically sealed type. Theassembly includes walls forming a heat insulation chamber surroundingthe noise reducing chamber with a substantially statically contained gasin said heat insulation chamber.

' The invention relates to a hermetically enclosed small refrigeratingmachine, theinterior of which is under suction pressure and the soundreducing unit of which is provided with means for limiting thedissipation of heat.

In a known construction of this kind, the means for limiting thedissipation of heat consist of a coating comprised of a film of plasticsmaterial, or of a porous layer of plastics material. This sheathingprevents the hot surface of the noise-reducing unit from being directlyswept by the suction gas, so that, due to the low heat-conductingcapacity of the filler material, the transfer of heat to the suction gasis reduced. Moreover, the surface of the noise-reducing unit isprevented from being wetted with oil, so that the transfer of heat tothe oil is also prevented. This results in the hot pressure gas carryinga fairly large proportion of its thermal energy outwards and the case iskept at a lower temperature. The sheathings of plastics material aredifficult to apply, however. They require steps which cannot readily beincorporated in the assembly-line method that is usually employed in themanufacture of such refrigerating machines and that consist mainly ofmetal-working operations. Furthermore, the sheathings of plasticsmaterial can suffer damage. The further machining and assemblyoperations, including the unavoidable welding operations, must thereforebe carried out with extra care.

A construction is also known wherein the noise-reducing unit, freelyswept by the suction gas, is positioned beneath a protective plate oranother component of the compressor in such a manner that it is largelyprotected against being wetted by sprayed oil. Here, direct heatexchangebetween the noise-reducing unit and the suction gas has to be accepted.

The object of the invention is to provide the noisereducing unit withmeans for limiting the dissipation of heat, which means can be readilyapplied in the normal production line handling small refrigeratingmachines, are largely immune from damage and nevertheless have a verygood effect as regards the prevention of heat-transfer.

According to the invention, this object is achieved by forming thelimiting means as a static gas-cushion, which is contained between thewall of the noise-reducing unit and a metal wall surrounding it atadistance therefrom. The metal wall prevents the surface of thenoise-reducing unit from being wetted by oil and prevents the suctiongas from sweeping said surface. Here, the metal wall itself may beheat-conducting and also be supported on the Patented May 23, 1972noise-reducing unit, since the area of contact is relatively small andthe whole of the rest of the surface is sep arated from thenoise-reducing unit by the thermally insulating gas-cushion. Since themetal Wall forms a rigid shaped part, the distance from the wall of thenoisereducing unit, i.e. the size of the gas-cushion, and therefore theeffect of the limitation of the heat-transfer can be predetermined quiteaccurately in terms of construction. a

In a preferred construction, the metal wall is soldered directly on tothe noise-reducing unit and the gas-cushion consists of the protectivegas used in the soldering. A subatmospheric pressure will have been setup in the enclosed gas-cushion compartment during cooling aftersoldering. The smaller number of gas molecules in the gas-cushionresults in a particularly poor heat-transfer.

In order to avoid having to deal with problems of soundness, however, itis also possible to provide an opening at the bottom of the metal walland to use the refrigerant gas as the gas-cushion. Since the refrigerantgas does not move, this likewise results in low heat-transfer.

Furthermore, use can be made of two noise-reducing chambers which areeach provided with a metal wall on one side only and which lie againsteach other at their other sides. Despite using only two gas-cushions,both noise-reducing chambers are fully protected against excessive heatdissipation.

It is also of advantage for at least two sheet-metal walls, defining anoise-reducing chamber, to have extensions which accommodate part of thepressure piping and form the cylinder head containing the pressure andsuction valve chambers, at least the cylinder head projecting beyond thezone of the metal walls enclosing the gas-cushion. By uniting thecylinder head and the noise-reducing unit manufacture is simplified.Additionally, the noise-reducing unit is held in a safe andvibration-free manner. In order to enable the suction valve chambers ofthe noise-reducing unit to be properly cooled, however, this part of thecomponent projects from the metal walls.

The invention will now be described in more detail by reference to anembodiment illustrated in the drawing, wherein:

FIG. 1 is a side elevation of a noise-reducing chamber according to theinvention, and FIgICi. 2 is a longitudinal section on the line AA ofAttached to the valve plate 1 of a cylinder 2 of an enclosed smallrefrigerating machine, which is positioned in the interior of a caseunder suction pressure, is a component 3 which forms a cylinder head 4and a noise-reducing unit 5.

The noise-reducing unit is composed of six sheet-metal shaped parts,which are all soldered together. A middle plate 6, together with adished sheet-metal part 8, forms a first noise-reducing chamber 7 on oneside and, together with a second dished sheet-metal part 10, forms asecond noise-reducing chamber 9 on the other side. Between the middleplate 6 and the sheet-metal part 8 is inserted a channel plate 11 which,together with the middle plate 6, forms throttle passages 12 for the gasentering the chamber 7 and for the gas passing into the chamber 9through an orifice, not illustrated, in the middle plate 6.

A limiting wall of the chamber 7 lies against a limiting wall of thechamber 9. The free limiting walls are covered by a first sheet-metalwall 13 for forming a gas-cushion chamber 14 and by a second sheet-metalwall 17 for forming a second gas-cushion chamber 16. These sheet-metalwalls are connected to the sheet-metal parts 8 and 10 only 'by a narrowedge portion 17 and 18 respectively. Openings 19 at the lower end of thesheet-metal wall 13 and similar openings at the lower end of thesheet-metal wall permit the refrigerant to pass into the gas-cushionchambers 14 and 16 and there to form a static gas-cushion.

The middle plate 6, the channel plate 11 and the first dishedsheet-metal part 8 project beyond the sheet-metal Walls 13 and 15 andform the cylinder head 3. For this purpose the middle plate 6 containstwo suction-gas orifices and 21 and a pressure-gas orifice 22. Thelatter is covered by a pressure-valve element 23. The channel plate 11incorporates protuberant portions, not visible in the drawing, whichseal off from each other suction-valve chambers associated with theorifices 20 and 21 and a pressure valve chamber 24 associated With theorifice 22. The pressure-valve chamber communicates with thenoisereducing unit by way of the pressure passage 25 which is likewiseformed between the channel plate 11 and the metal plate 6. The orifices20 and 21 serve both to supply suction gas through passages in the valveplate 1 and to introduce the suction gas into the cylinder 2 by way ofthe valve plate. The pressure gas is discharged from the noise-reducingunit through a pipe 26.

The middle plate 6 has at its edge tabs 27, which are bent over to oneside, alternating therewith, tabs 28 bent over to the other side. Theremaining sheet-metal parts 8, 10, 11, 13 and 15, contain slots 29adapted to receive the tabs 27 and 28. For assembling the component 3,the prepared sheet-metal parts 8, 10, 11, 13 and 15 are simply pushed onto the middle plate 6 from both sides, their positions being accuratelydefined by the tabs 27 and 28 and the slots 29. The parts are then heldtogether by the application of light pressure and passed through asolder ing furnace and soldered together, a very stable component 3 thenresulting.

We claim:

1. A noise reducing assembly for a refrigeration unit of thehermetically sealed type in which the interior thereof is undersubatmospheric pressure during operation of the unit, comprising, acompressor, first nnperforated wall means forming a noise reducingchamber for receiving a refrigerant gas exhausted by said compressor,second unperforated wall means in spaced relation to said first wallmeans forming an outer insulating chamber for said noise reducingchamber, a gas substantially statically contained in said outer chamber,said second wall means being soldered to said first wall means and saidgas being a protective gas of the type used for soldering.

2. A noise reducing assembly for a refrigeration unit of thehermetically sealed type in which the interior there-, of is undersubatrnospheric pressure during operation of the unit, comprising, acompressor, first unperforated wall means forming a noise reducingchamber for receiving a refrigerant gas exhausted by said compressor,second wall means in spaced relation to said first wall means forming anouter insulating chamber for said noise reducing chamher, a refrigerantgas substantially statically contained in said outer chamber, saidsecond wall means having an opening formed therein for admitting arefrigerant gas to said outer chamber.

References Cited MARTIN P. SCHWADRON, Primary Examiner I. C. COHEN,Assistant Examiner U.S. Cl. X.R. 62-296; 417-902

